Patent GB-861658-A (GB)
Title: Improvements in or relating to magnetic core circuits for handling binary information
IPC: G11C19/04
Filed: 1957-07-19
Abstract: 861,658. Circuits employing bistable magnetic cores. SOC. D'ELECTRONIQUE ET D'AUTOMATISME. July 19, 1957 [July 21, 1956; Sept. 5, 1956; Oct. 31, 1956; Feb. 5, 1957], No. 22931/57. Class 40 (9). A device for handling binary-coded information comprises a plurality of cascade-connected rectangular hysteresis loop cores having transfer circuits comprising write-in and read-out windings interconnected by similarly-poled rectifiers stepping being effected by a twopolarity voltage wave form successive transfer circuits being supplied with the said waveform in opposite phase. In a first embodiment, Fig. 1, circuits 1 ... 4 are pulsed successively. The cores are so arranged that their directions of saturation are such that when a 1 is registered on them they present low impedance to the pulses on circuits 1 or 3 so that current flows in the transfer circuits via low impedance read-out windings 5 and write-in windings 6 so that the succeeding cores are set. The subsequent pulses in circuits 2 or 4 reset the cores originally carrying the digit 1, the digit thus being stepped on one core. Digits are intended to be originally inserted on alternate cores so that two cores per registration are needed. The number of turns of a read-out winding 5 is greater than the number of turns of a write-in winding 6. Thus in the case of the transfer of a 0 it ensures that the core associated with the coil 5 reaches the vertical part of the hysteresis loop before the core associated with the coil 6, so that no change of state of the former occurs. Moreover this relationship ensures that on reset the effect on the preceding core is small. In a second embodiment, Fig. 8, in which there is no separate resetting phase the digit 1 is represented by opposite polarities on alternate cores and the read-out current of a core is used to reset the core. Thus during any half-cycle in which a rectifier is conducting, the core of the read-out winding associated therewith is restored to the " N " condition (or remains in that condition). If the core I (say) prior to this cycle was in a " P " condition then the readout winding impedance is high and the write-in current for the succeeding current is small so that this core remains in the " N " condition. If the core I was in the " N " condition then its impedance is low and the succeeding core has a large write-in current to change it to the " P " condition. Thus a digit 1 is stepped from core to core being alternately represented by P and N conditions. A self-biasing circuit 15 may be provided to emphasize the negative half-cycle as compared with the positive halfcycle. This is provided to counteract a spurious voltage induced in neighbouring circuits, when a core reaches saturation with a consequent sudden increase in current in the circuit containing the core which has just saturated. If such biasing may be dispensed with the A.C. supply may be from two wires, the connections being reversed in alternate transfer circuits. Such a manner of connection is shown in Fig. 10 which also illustrates a read-out circuit. Thus cores IX and VI are set in identical manner from the read out of V and on the next half-cycle the setting of IX is transferred to VIII at the same time as the setting of VI is transferred to the succeeding core in the chain. Core IX may be provided with an additional winding so poled as to provide either an OR or as an inhibition relation between the additional input and the read-out received from the stepping circuit. In a modification, Fig. 12, suitable for combining several inputs according to a logical function an additional core XI is used in the transfer circuit from core VI to core X and a cross-over is introduced in the transfer circuit between V and VI. Thus let digits 1, 0 correspond to a high and low value of current in the transfer circuit between V and VI during the positive phase of current 1. Thus in the case of digit 1 during the +ve phase of current 1 and the - ve phase of current 3 their effects on core VI cancel out and core XI has its polarity reversed. During the subsequent +ve phase of current 3 core VI presents a low impedance and XI presents a high shunt impedance so that current flows to the read-in winding of X to set it with the digit 1. Core XI is also reset during this period. In the case of digit 0 core VI is solely effected by the - ve phase of current 3 and reverse its polarity but XI remains unchanged. Therefore, during the +ve phase of current 3 the read-out winding of VI presents a high series impedance and core XI a low shunt impedance so that core X is uneffected. Core VI is however reverted to its normal state. Several windings 5 may be connected in series or parallel or combinations thereof in order to produce logical functions of the various outputs of several stepping registers.